Search results for "SHELL"
showing 10 items of 748 documents
Core-Shell Microgels with Switchable Elasticity at Constant Interfacial Interaction.
2016
Hydrogels based on poly(N-isopropylacrylamide) (pNIPAAm) exhibit a thermo-reversible volume phase transition from swollen to deswollen states. This change of the hydrogel volume is accompanied by changes of the hydrogel elastic and Young's moduli and of the hydrogel interfacial interactions. To decouple these parameters from one another, we present a class of submillimeter sized hydrogel particles that consist of a thermosensitive pNIPAAm core wrapped by a nonthermosensitive polyacrylamide (pAAm) shell, each templated by droplet-based microfluidics. When the microgel core deswells upon increase of the temperature to above 34 °C, the shell is stretched and dragged to follow this deswelling i…
Tuning the defect configurations in nematic and smectic liquid crystalline shells
2013
Thin liquid crystalline shells surrounding and surrounded by aqueous phases can be conveniently produced using a nested capillary microfluidic system, as was first demonstrated by Fernandez-Nieves et al. in 2007. By choosing particular combinations of stabilizers in the internal and external phases, different types of alignment, uniform or hybrid, can be ensured within the shell. Here, we investigate shells in the nematic and smectic phases under varying boundary conditions, focusing in particular on textural transformations during phase transitions, on the interaction between topological defects in the director field and inclusions in the liquid crystal (LC), and on the possibility to rel…
Structural and chemical characterization of CdSe-ZnS core-shell quantum dots
2018
Abstract The structural and compositional properties of CdSe-ZnS core-shell quantum dots (QDs) with a sub-nm shell thickness are analyzed at the atomic scale using electron microscopy. QDs with both wurtzite and zinc blende crystal structures, as well as intermixing of the two structures and stacking faults, are observed. High-angle annular dark-field scanning transmission electron microscopy suggests the presence of a lower atomic number epitaxial shell of irregular thickness around a CdSe core. The presence of a shell is confirmed using energy dispersive X-ray spectroscopy. Despite the thickness irregularities, the optical properties of the particles, such as photoluminescence and quantum…
Fermi energy dependence of the optical emission in core/shell InAs nanowire homostructures.
2017
InAs nanowires grown by vapor–liquid–solid (VLS) method are investigated by photoluminescence. We observe that the Fermi energy of all samples is reduced by ~20 meV when the size of the Au nanoparticle used for catalysis is increased from 5 to 20 nm. Additional capping with a thin InP shell enhances the optical emission and does not affect the Fermi energy. The unexpected behavior of the Fermi energy is attributed to the differences in the residual donor (likely carbon) incorporation in the axial (low) and lateral (high incorporation) growth in the VLS and vapor–solid (VS) methods, respectively. The different impurity incorporation rate in these two regions leads to a core/shell InAs homost…
Reddening map around ? Orionis
1990
uvbyβ photometry has been done for early-type stars in the surroundings of the shell star α Ori. The reddening maps show the presence of irregularly distributed absorbing material.
Synthesis of low density foam shells for inertial confinement fusion experiments
2011
This work deals with the fabrication process of low density foam shells and the sharp control of their shape (diameter, thickness, density, sphericity, non-concentricity). During this PhD we focused on the non-concentricity criterion which has to be lower than 1%. The shells are synthesized using a microencapsulation process leading to a double emulsion and followed by a thermal polymerization at 60°C. According to the literature, three major parameters, the density of the three phases, the deformations of the shells along the process and the kinetics of the polymerization have a direct influence on the shells non-concentricity. The results obtained showed that when the density gap between …
Solar neutrino detection in liquid xenon detectors via charged-current scattering to excited states
2020
We investigate the prospects for real-time detection of solar neutrinos via the charged-current neutrino-nucleus scattering process in liquid xenon time projection chambers. We use a nuclear shell model, benchmarked with experimental data, to calculate the cross sections for populating specific excited states of the caesium nuclei produced by neutrino capture on $^{131}$Xe and $^{136}$Xe. The shell model is further used to compute the decay schemes of the low-lying $1^{+}$ excited states of $^{136}$Cs, for which there is sparse experimental data. We explore the possibility of tagging the characteristic de-excitation $\gamma$-rays/conversion electrons using two techniques: spatial separation…
High-Statistics Sub-Barrier Coulomb Excitation of $^{106,108,110}$Sn
2020
International audience; A Coulomb excitation campaign on $^{106,108,110}$Sn at 4.4–4.5 MeV/u was launched at the HIE-ISOLDE facility at CERN. Larger excitation cross sections and γ-ray statistics were achieved compared to previous experiments at ∼2.8 MeV/u. More precise $(B(E2;0_{1}^{ + } \to 2_{1}^{ + }))$ values, lifetimes of states via the Doppler shift attenuation method, and new $(B(E2;0_{1}^{ + } \to 2_{x}^{ + })), (B(E2;2_{1}^{ + } \to 4_{1}^{ + }))$ and $(Q(2_{1}^{ + }))$ values from the new Miniball data will be obtained and applied to test modern nuclear structure theories.
gA -driven shapes of electron spectra of forbidden β decays in the nuclear shell model
2017
The evolution of the shape of the electron spectra of 16 forbidden ${\ensuremath{\beta}}^{\ensuremath{-}}$ decays as a function of ${g}_{\mathrm{A}}$ was studied using the nuclear shell model in appropriate single-particle model spaces with established, well-tested nuclear Hamiltonians. The $\ensuremath{\beta}$ spectra of $^{94}\mathrm{Nb}({6}^{+})\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}^{94}\mathrm{Mo}({4}^{+})$ and $^{98}\mathrm{Tc}({6}^{+})\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}^{98}\mathrm{Ru}({4}^{+})$ were found to depend strongly on ${g}_{\mathrm{A}}$, which makes them excellent candidates for the determination of the effective value of ${g}_{\mathrm{A}}$ wit…
Second-forbidden nonunique β− decays of Na24 and Cl36 assessed by the nuclear shell model
2020
We have performed a systematic study of the $logft$ values, shape factors, and electron spectra for the second-forbidden nonunique ${\ensuremath{\beta}}^{\ensuremath{-}}$ decays of $^{24}\mathrm{Na}({4}^{+})\ensuremath{\rightarrow}^{24}\mathrm{Mg}({2}^{+})$ and $^{36}\mathrm{Cl}({2}^{+}){\ensuremath{\rightarrow}}^{36}\mathrm{Ar}({0}^{+})$ transitions under the framework of the nuclear shell model. We have performed the shell model calculations in the $sd$ model space, using more recent microscopic effective interactions such as Daejeon16, chiral N3LO, and JISP16. These interactions are derived from the no-core shell model wave functions using Okubo-Lee-Suzuki transformation. For comparison,…